Healthy teachers are a basic prerequisite for successful educational processes. ATLAS (Associations between Teachers' Psychological Strain and Allostatic Load, the Classroom Environment, And Student Development) investigates the relationship between psychophysiological stress in teachers, the classroom environment and the development of students with the aim of preventing negative health consequences and improving the quality of education. The study is being conducted in cooperation with the Universities of Bern, Greifswald and Montréal. It will start in April 2025 and last four years.